President Woodrow Wilson's behavior was affected by decreased blood flow to the brain during his oft-criticized and ultimately futile campaign to have the United States join the League of Nations, a historian says.

Records that were never made public show that Wilson was disabled by illness during the critical period in U.S. history after World War I, said Princeton University history Professor Arthur Link, editor of a series of volumes of Wilson's papers."It is one of the great tragedies of the 20th century," Link said in a recent interview. "The man who was most responsible for building support for the idea of a League of Nations was struck down just as his leadership was most needed. And he was struck down by events over which he had no control."

The 64th volume in the series, to be published in February, will reveal for the first time detailed medical records kept by Dr. Cary T. Grayson, Wilson's personal physician.

Link said the records, with analysis by medical experts, explain Wilson's poor performance in the months leading up to his devastating stroke in October 1919.

Wilson, a Democrat, was president from 1913 to 1921. He died in 1924.

He won the 1919 Nobel Peace Prize for his peacemaking efforts involving the League of Nations after World War I. However, he failed to win U.S. support for the League, which fell apart before World War II.

"In a world with the United States playing a responsible, active role, the possibilities of preventing the rise of Hitler were limitless," Link said.

Wilson failed to get the Senate to ratify U.S. membership in the league because of what Link said was an uncharacteristic unwillingness to compromise. The Senate wanted guarantees that the United States would not be subordinate to the votes of other nations in case of war.